System and method for input power detection of two power sources using single monitoring circuit

ABSTRACT

A voltage supply system that includes a first power supply branch and a second power supply branch. Both branches includes a voltage supply; a serially connected diode and switch connected between the voltage supply and an output of the voltage supply system; and a gate driver connected to the first switch to control operation of the switch. The system also includes a voltage monitor/controller configured to perform a built-in test of the system by controlling the state of the first and second switches by controlling enable signals provided to the first and second gate drivers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Indian Patent Application No.202211006908 filed Feb. 9, 2022, the entire contents of which isincorporated herein by reference.

BACKGROUND

Exemplary embodiments of the present disclosure pertain to the art ofsupplying power and, in particular, to testing two or more redundantpower sources with a single circuit.

A number of applications, such as safety critical avionics, make use ofindependent, redundant power input sources. In the event that one ormore of the input sources fails, another of the available redundantpower input sources is employed to ensure an uninterrupted supply ofpower.

In such systems, the two input voltages are typically connected in “OR”using diodes. To ensure that both input voltage are working, the inputvoltage of sources usually separately measured at input point (beforethe diode). That is, in prior art systems, voltage monitoring of twosources is done using two different voltage monitoring circuits.

BRIEF DESCRIPTION

Disclosed is a voltage supply system that includes: a first power supplybranch and a second power supply branch. The first power supply branchincludes: a first voltage supply; a serially connected first diode andfirst switch connected between the first voltage supply and an output ofthe voltage supply system; and a first gate driver connected to thefirst switch to control operation of the first switch. The second powersupply branch includes: a second voltage supply; a serially connectedsecond diode and second switch connected between the second voltagesupply and the output of the voltage supply system; and a second gatedriver connected to the second switch to control operation of the firstswitch. The system also includes a voltage monitor/controller configuredto perform a built-in test of the system by controlling the state of thefirst and second switches by controlling enable signals provided to thefirst and second gate drivers.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the gate drivers canreceive power from their respective power supplies.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the first gate driverincludes a first enable input (EN1) and the second gate driver includesa second enable input (EN2), wherein the first gate driver causes thefirst switch to conduct when it receives a signal at EN1 and the secondgate driver causes the second switch to conduct when it receives asignal at EN2.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the voltage monitorcontroller includes logic that controls the built in test.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the logic causes thesystem to operate in a first state where both the first and second gatedrives are enabled to cause both the first and second switches to beconductive.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the logic determinesthat neither of the first and second voltage sources are operationalwhen the voltage monitor measures a voltage below an expected voltagewhile the system is in the first state.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the logic determinesthat at least one of the first and second voltage sources areoperational when the voltage monitor measures an expected voltage whilethe system is in the first state.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, when the logicdetermines that at least one of the first and second voltage sources areoperational, the logic cycles to a second state where the first gatedriver is enabled and the first switch is conductive and the second gatedriver is disabled.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the logic determinesthat the first voltage source has failed and returns the system to thefirst state if the voltage monitor measures a value that falls below anexpected value.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the logic determinesthat the first voltage source is operational when the voltage monitormeasures an expected voltage while the system is in the second state andthen cycles into a third state wherein the first gate driver is disable,the second gate driver is enabled and the second switch is conductive.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the logic determinesthat the second voltage source has failed and returns the system to thefirst or second state if the voltage monitor measures a value that fallsbelow an expected value.

Also disclosed is method of testing a voltage supply system with asingle circuit. The method includes: providing a system as claimed inclaim 1, wherein the first gate driver includes a first enable input(EN1) and the second gate driver includes a second enable input (EN2),wherein the first gate driver causes the first switch to conduct when itreceives a signal at EN1 and the second gate driver causes the secondswitch to conduct when it receives a signal at EN2; causing the systemto operate in a first state where both the first and second gate drivesare enabled to cause both the first and second switches to beconductive; and measuring a voltage at an output of the system with thevoltage monitor.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the method can alsoinclude determining that neither of the first and second voltage sourcesare operational when the voltage monitor measures a voltage below anexpected voltage while the system is in the first state.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the method can alsoinclude determining that at least one of the first and second voltagesources are operational when the voltage monitor measures an expectedvoltage while the system is in the first state.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, in the method, when atleast one of the first and second voltage sources are operational,switching the circuit to a second state where the first gate driver isenabled and the first switch is conductive and the second gate driver isdisabled.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the method can alsoinclude determining that the first voltage source has failed and returnsthe system to the first state if the voltage monitor measures a valuethat falls below an expected value.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the method can alsoinclude: determining that the first voltage source is operational whenthe voltage monitor measures an expected voltage while the system is inthe second state; and cycling into a third state wherein the first gatedriver is disable, the second gate driver is enabled and the secondswitch is conductive.

In addition to one or more of the features described above, or as analternative to any of the foregoing embodiments, the method can alsoinclude determining that the second voltage source has failed andreturning the system to the first or second state if the voltage monitormeasures a value that falls below an expected value.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is an example of a prior art OR connection of two power sourcessupplying power to an output; and

FIG. 2 is simplified circuit diagram of an OR connection of two powersources supplying power to an output including the testing circuitryaccording one or more embodiments.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

As discussed above, it is common for the two input voltages to beconnected in an “OR” configuration using diodes. To ensure that bothinput voltage are working, the status of each voltage source istypically measured with its own voltage monitor. That is, voltagemonitoring of two sources is done using two different voltage monitoringcircuit.

Embodiments herein disclose a system which can detect the two differentvoltage sources with a single monitoring circuit. This can be donewithout interrupting the input power to the drive device (assuming atleast one of the sources is operational).

FIG. 1 shows a prior art system 100 that has two sources V_1/V_2connected in a so-called “OR” configuration. The diodes D1 and D2provide a configuration that allows either or both of V_1/V_2 to drivethe output line 102. Also included is an output capacitor C1 to smooththe output at start up and in the event one of the sources fails. Othercircuit elements are self-explanatory to the skilled artisan based onFIG. 1 . For completeness, it is noted that an output voltage monitorVM3 can also be provided that measures the voltage output.

To ensure that each voltage source V_1/V_2 is operating properly, eachvoltage source is connected to a separate, respective, voltage inputmonitor VM1 and VM2. Having separate monitor for each voltage sourceV_1/V_2 can increase cost and complexity. Further, as shown by leakagepath 104, in some instances diode leakage current can lead to anerroneous indication that V_2 is operational even if it has failed. Ofcourse, the opposite leakage path could also present a V_1 error.

In addition to the abovementioned single circuit operation, embodimentsherein may avoid the above-described operational error due to leakagecurrent.

In the above and the below, V_1/V_2 can be provided by, for example,rectified generator voltages, batteries or both (e.g., V_1 can berectified power from an AC supply and V_2 can be a battery).

FIG. 2 shows a simplified circuit 200 that can test two “OR” connectedvoltage sources V_1/V_2. The circuit 200 includes two series connectedflow control devices connected to the output of each voltage sourceV1/V2. As illustrated, the combination is formed by a series combinationof a diode and a switch. Of course, other combinations could be use suchas two switches and, in particular, complementary switches. The outputof the respective switches can be connected together for each voltagesource resulting in “OR” connected dual power supply system. The pointof connection is generally shown as ORing point 201. It shall beunderstood that other circuit elements can be connected between theoutputs of the switches and the ORing point 201 that is also connectedto the output 202 of the circuit 200. The voltage at the ORing point201/output 202 can be monitored by a voltage monitor/controller 204 thatmeasures voltages at the ORing point 201 and controls the status of theswitches. The voltage monitor/controller 204 can be single monitor inone embodiment.

As will be understood, having the combination of a diode and a switchhelps to stop the flaw of leakage current from one source to another toovercome at least one the above discussed possible shortcomings of theprior art.

As illustrated, the circuit 200 includes first and second power supplybranches 206, 208. Both have outputs connected to the ORing point 201and, as will be understood by the skilled artisan, can either alone orcombination drive the output 202. The output 202/ORing point 201 can becoupled to ground via an output capacitor C1.

The first power supply branch 206 includes the first power supply V_1.V_1 connected to the output 202 via a series connection of a first diodeD1 and first switch S1. The first power supply branch 206 also includesa first gate driver 210. The gate driver controls the status of thefirst switch S1 and includes an input 212, an output 214, and an enableEN1. The output 214 of the gate driver 210 is connected to the firstswitch S1 and controls its condition/state (e.g., open or closed). Innormal operation, the first gate driver 210 places the first switch S1into a conductive or closed condition so that power from the first powersupply V_1 can pass through the first diode D1 and the first switch S1to reach the ORing point 201.

As shown, the circuit 200 includes the voltage monitor/controller 204.The voltage monitor/controller 204 is connected to enable EN1. Thisconnection will allow for testing as discussed below.

The input 212 of the first gate driver 210 is connected to the firstpower supply V_1. When enabled by EN1 the first gate driver 210 usesinput power from V_1 and enables the first switch S1. Of course, thefirst gate driver could be provided power from a different source.

The second power supply branch 208 includes the second power supply V_2.V_2 connected to the output 202 via a series connection of a seconddiode D2 and second switch S2. The second power supply branch 208 alsoincludes a second gate driver 216. The second gate driver 216 controlsthe status of the second switch S2 and includes an input 218, an output222, and an enable EN2. The output 222 of the second gate driver 216 isconnected to the second switch S2 and controls its condition/state(e.g., open or closed). In normal operation, the second gate driver 216places the second switch S2 into a conductive or closed condition sothat power from the second power supply V_2 can pass through the firstdiode D1 and the first switch S1 to reach the ORing point 201.

Similar to the above, the voltage monitor/controller 204 is connected toenable EN2 of the second gate driver 216. This connection will allow fortesting as discussed below. As shown, the input 218 of the second gatedriver 216 is connected to the second power supply V_2. When enabled byEN2 the second gate driver 216 uses input power from V_2 and enables thesecond switch S2. Of course, the second gate driver could be providedpower from a different source. Thus, the first and second gate driverscan share a separate power supply or have their own as alternatives towhat is shown in the FIG. 2 .

As noted above, the first and second gate drivers 210, 216 are connectedto and receive power from their respective power sources V-1, V_2. Thus,if the power sources are not providing power, the gate driver cannotcause its associated switch (S1/S2) to close regardless of the value ofthe associated enable signal.

The voltage monitor 204 can include testing logic 220 that can allow themonitor 204 to determine the status of each power supply V_1/V_2 with asingle monitor. This is done, for example, by controlling the signalsprovided to EN1/EN2 and measuring the voltage at the output 202. Itshall be understood that because controlling EN1/EN2 can open switchesS1/S2, the first and second power supply branches 206, 208 canessentially be isolated from one another so error due to leakage currentcan be reduced or eliminated.

Reference is now made to FIG. 2 and Table 1 below. In one embodiment,the testing logic 220 of the voltage monitor/controller 204 can beprogrammed so that it can perform a built in test (BIT) to determine ifthe status of each power supply V_1/V_2. In particular, the testinglogic can follow control the signals provided to EN1 and EN2. An exampleof such a sequence and related observations is shown in Table 1 below.It shall be understood that different sequences could be utilized.

TABLE 1 BIT test and observation of input voltage source availabilityBIT Reading at OR En1 En2 point 201 Conclusion State 0 0 0 InitialCondition State 1 1 1 Power Available Either VM1 or VM2 or both ispresent Power not Available Both sources are not available State 2 1 0Power Available VM1 is available and measurement on ORing point showsvoltage level of 1st source Power decaying VM1 is not available. towardszero Switch back to state 1 as soon as voltage is below critical level(e.g., 16 V) State 3 0 1 Power Available VM2 is available andmeasurement on ORing point 201 shows voltage level of VM2 Power decayingVM2 is not available. towards zero Switch back to state 1 as soon asvoltage is below critical level (16 V)

As shown, the BIT sequence and observation result from each state islisted in Table 1. Initial state is ‘state 0’ in which EN1=0 and EN2=0.The next state is state 1. In ‘state 1’ both switches S1 & S2 areenabled by making EN1=1 and EN2=1. At this state there are twopossibilities at ORing point 201. If an expected voltage (e.g., 28V) isavailable then either or both input sources V_1/V_2 are available. Ifthere is voltage, then neither voltage source V_1/V_2 is available. Insuch a case, a failure of both can be noted and the BIT can cease.

To check the individual source availability, the logic 220 cycles to thenext state (state 2). In this state, switches S1 is kept ON and switchS2 is turned OFF by making EN1=1 and EN2=0. If the expected is availableat ORing point 201, then it is known that V_1 is functioning correctlyas it is the only one providing power point 201 in this configuration.If V_1 is failed, then the voltage at point 201 will start to falltowards zero then it indicates that source V_1 is not available andvoltage at 28V_OR should be monitored. As soon as voltage go below acritical lower limit (e.g., 16V), system should go back to state 1 whichwill ensure the power is not interrupted at 28V_OR point. The voltagedrop is not instantaneous due to C1. This can allow for testing withoutinterruption of the power to the output 202.

In ‘state 3’ switch S1 is turned OFF and switch S2 is turned ON bymaking EN1=0 and EN2=1. If a desired voltage (e.g., 28 V) is availableat point 201 then availability of V_2 is guaranteed and reading ofvoltage level is assigned to voltage level of source V_2. If, however,the voltage starts falling towards zero then it indicates that V_2 isnot available. As above, in the event that voltage falls below acritical lower limit the system goes back to state 1 which will ensurethe power is not interrupted at point 201. State 1 can be referred to asa normal operational state herein.

It shall be understood that while the above table has the system cycleback to a state 1, there could be instances where it cycles to eitherstate 2 or 3 depending on which voltage source has failed withoutdeparting from the teachings herein.

It should be further noted that the results of any test performed can beconveyed to another device 240. In one embodiment, the device 240 is acomputer in an aircraft. The device can note the status of the voltagessources and create, if needed, a service request or take other remedialactions.

The circuit shown herein two input power sources using a singlemonitoring circuit, while the prior arts having two monitoring circuits.Further, occurrence of false indications due to leakage current can beeliminated. Also, the monitoring circuit also makes it possible to onlyone or both of the power sources V_1, V_2 periodically to alternativelyutilize power from both sources or to use it from both at the same time.Using both at the same time can be useful in improving thermalmanagement of overall system by sharing power from both sources.

It should be understood that the monitor/controller 204 can includevarious sensors (e.g., voltage sensors 205). The controller 204 can beformed as a processes that is a hardware device for executing software,particularly that stored in storage, such as cache storage, or memory.The processor can be any custom made or commercially availableprocessor, a central processing unit (CPU), an auxiliary processor amongseveral processors associated with the controller, a semiconductor basedmicroprocessor (in the form of a microchip or chip set), amicroprocessor, or generally any device for executing instructionsstored in logic 220. The logic 220 can also either access memory of thecontroller or have its own memory. Regardless it can be configured toeither on command or automatically/periodically perform a self test ofthe power sources V_1, V_2.

The memory can include any one or combination of volatile memoryelements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM,etc.)) and nonvolatile memory elements (e.g., ROM, erasable programmableread only memory (EPROM), electronically erasable programmable read onlymemory (EEPROM), programmable read only memory (PROM), tape, compactdisc read only memory (CD-ROM), disk, diskette, cartridge, cassette orthe like, etc.). Moreover, the memory may incorporate electronic,magnetic, optical, and/or other types of storage media. Note that thememory can have a distributed architecture, where various components aresituated remote from one another, but can be accessed by the processor.

The instructions in logic 220 may include one or more separate programs,each of which comprises an ordered listing of executable instructionsfor implementing logical functions as described above.

The term “about” is intended to include the degree of error associatedwith measurement of the particular quantity based upon the equipmentavailable at the time of filing the application.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. A voltage supply system comprising: a first powersupply branch that includes: a first voltage supply; a seriallyconnected first diode and first switch connected between the firstvoltage supply and an output of the voltage supply system; and a firstgate driver connected to the first switch to control operation of thefirst switch; a second power supply branch that includes: a secondvoltage supply; a serially connected second diode and second switchconnected between the second voltage supply and the output of thevoltage supply system; and a second gate driver connected to the secondswitch to control operation of the first switch; and a voltagemonitor/controller configured to perform a built-in test of the systemby controlling the state of the first and second switches by controllingenable signals provided to the first and second gate drivers.
 2. Thesystem of claim 1, wherein the gate drivers receive power from theirrespective power supplies.
 3. The system of claim 2, wherein the firstgate driver includes a first enable input (EN1) and the second gatedriver includes a second enable input (EN2), wherein the first gatedriver causes the first switch to conduct when it receives a signal atEN1 and the second gate driver causes the second switch to conduct whenit receives a signal at EN2.
 4. The system of claim 3, wherein thevoltage monitor controller includes logic that controls the built intest.
 5. The system of claim 4, wherein the logic causes the system tooperate in a first state where both the first and second gate drives areenabled to cause both the first and second switches to be conductive. 6.The system of claim 5, wherein the logic determines that neither of thefirst and second voltage sources are operational when the voltagemonitor measures a voltage below an expected voltage while the system isin the first state.
 7. The system of claim 5, wherein the logicdetermines that at least one of the first and second voltage sources areoperational when the voltage monitor measures an expected voltage whilethe system is in the first state.
 8. The system of claim 7, wherein whenthe logic determines that at least one of the first and second voltagesources are operational, the logic cycles to a second state where thefirst gate driver is enabled and the first switch is conductive and thesecond gate driver is disabled.
 9. The system of claim 8, wherein thelogic determines that the first voltage source has failed and returnsthe system to the first state if the voltage monitor measures a valuethat falls below an expected value.
 10. The system of claim 9, whereinthe logic determines that the first voltage source is operational whenthe voltage monitor measures an expected voltage while the system is inthe second state and then cycles into a third state wherein the firstgate driver is disable, the second gate driver is enabled and the secondswitch is conductive.
 11. The system of claim 10, wherein the logicdetermines that the second voltage source has failed and returns thesystem to the first or second state if the voltage monitor measures avalue that falls below an expected value.
 12. A method of testing avoltage supply system with a single circuit, the method comprising:providing a system as claimed in claim 1, wherein the first gate driverincludes a first enable input (EN1) and the second gate driver includesa second enable input (EN2), wherein the first gate driver causes thefirst switch to conduct when it receives a signal at EN1 and the secondgate driver causes the second switch to conduct when it receives asignal at EN2; causing the system to operate in a first state where boththe first and second gate drives are enabled to cause both the first andsecond switches to be conductive; and measuring a voltage at an outputof the system with the voltage monitor.
 13. The method of claim 12,further comprising: determining that neither of the first and secondvoltage sources are operational when the voltage monitor measures avoltage below an expected voltage while the system is in the firststate.
 14. The method of claim 12, further comprising: determining thatat least one of the first and second voltage sources are operationalwhen the voltage monitor measures an expected voltage while the systemis in the first state.
 15. The method of claim 14, wherein, when atleast one of the first and second voltage sources are operational,switching the circuit to a second state where the first gate driver isenabled and the first switch is conductive and the second gate driver isdisabled.
 16. The method of claim 15, further comprising: determiningthat the first voltage source has failed and returns the system to thefirst state if the voltage monitor measures a value that falls below anexpected value.
 17. The method of claim 15, further comprising:determining that the first voltage source is operational when thevoltage monitor measures an expected voltage while the system is in thesecond state; and cycling into a third state wherein the first gatedriver is disable, the second gate driver is enabled and the secondswitch is conductive.
 18. The method of claim 17, further comprising:determining that the second voltage source has failed and returning thesystem to the first or second state if the voltage monitor measures avalue that falls below an expected value.